Local Oscillator Spur Suppression in Phased Array Systems
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Solution Overview
Problem
Phased array systems face the issue of local oscillator (LO) spurs interfering with the desired signal due to coherent combination of LO signals from transceivers, leading to signal degradation.
Innovation Solution
Incorporating a LO spur suppression circuit that adjusts the phase of the LO signal and corresponding digital baseband signal to either direct the LO energy in an innocuous direction or spatially spread it, using phase shifter and phase adjustment value generator circuitry to mitigate LO spur interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If LO signals from multiple transceivers are coherently combined to improve signal strength, then transmit power is improved, but LO spurs are generated that interfere with the desired signal
Solution Approach 1:
The patent changes the phase parameter of individual LO signals by introducing phase rotation values to each transceiver's LO signal. This phase modification causes LO leakage signals to combine incoherently or cancel out, thereby suppressing LO spurs while preserving the coherent combination of desired transmit signals for maintaining high power output.
Solution Approach 2:
Instead of attempting to eliminate LO leakage at the source, the patent inverts the approach by deliberately introducing controlled phase differences that cause the harmful LO spur signals to cancel each other out through destructive interference, while the desired signals continue to combine constructively.
2Object-generated harmful factors
If phase adjustment is applied to suppress LO spurs, then LO spur interference is reduced, but signal quality may be affected
Solution Approach 1:
The patent applies different phase rotation values to different transceivers based on their individual characteristics and positions in the array. This localized phase adjustment ensures that each transceiver's LO leakage is suppressed appropriately without uniformly affecting all signals, thereby maintaining signal quality while reducing LO spurs.
Solution Approach 2:
The system measures or estimates the phase rotation values needed to suppress LO spurs and applies these adjustments to the LO signals. This feedback mechanism ensures that the phase corrections are optimized to maintain signal quality while achieving LO spur suppression, preventing degradation of the desired signal.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively suppresses LO spurs, preventing interference with the desired signal by either directing or spreading LO energy away from the main lobe, thereby enhancing signal quality and reducing degradation.
Implementation Method 1
Incorporating a LO spur suppression circuit that adjusts the phase of the LO signal and corresponding digital baseband signal to either direct the LO energy in an innocuous direction or spatially spread it
Data Source
AI summary
A system comprises local oscillator spur suppression circuitry, local oscillator generator circuitry), and beamforming circuitry. The local oscillator spur suppression circuitry is operable to generate a phase adjustment value. The local oscillator generator circuitry is operable to generate a local oscillator signal at a determined phase equal to a reference phase offset by the phase adjustment value. The beamforming circuitry is operable to receive the phase adjustment value, and generate a beamforming coefficient to be applied to a signal that is to be upconverted by the local oscillator signal and transmitted via an antenna element of a phased array, wherein the generation of the beamforming coefficient is based on the phase adjustment value and a location of the antenna element within the phased array.